The field of connective elements is very comprehensive. Even within the restricted field of attachment of ropes or rods to each other a large number of varieties have been conceived of.
One basis for separating such means of attachment is according to the angle formed by the two ropes or corresponding elements to be joined. The problem of connecting two similar ropes or corresponding elements perpendicularly to each other or to join them in parallel has more solutions than other types of problems of the same nature. In some cases several functions are combined in one element and in some cases the element is designed so as to permit the turning of one of the ropes about some axis in relation to the other rope.
Obviously, different reasons for joining ropes or the like cause different demands to be put on the attachment and the connective element. The dimensions of the connective element is strongly dependent on the dimensions of the rope or corresponding element. It is also significant whether the rope or corresponding element is soft or hard, stiff or flexible.
If the intention is to make a net of rope or string the classical method is to joint the strands by means of knots. When making large nets this is very time-consuming and laborious. The need for simple, easily assembled substitutes for the knots is great.
In some cases, the attachment must permit disassembly and reassembly.
Sometimes, the attachment requires special assembling tools.
The mass, volume, and cost of the connective element are very important in this context as in others.
Examples of prior art may be found in the following patent publications: U.S. Pat. 3,903,574 and DE No. 28 32 300, relating to perpendicular attachment using deformable metal clips; U.S. Pat. No. 3,747,166 and DE No. 20 58 099, relating to attachment devices which permit changing the angle between the strands after they have been put together, the former involving flexible plastic, the latter deformable metal; DE No. 25 49 939 relating to a very simple attachment by means of a piece of wire which is bent around the point of attachment; and U.S. Pat. No. 3,952,376 and 2,976,592, which relates to the joining of parallel ropes or corresponding elements.